This invention relates generally to a plating structure and a method for manufacturing pin grid array packages and, more particularly relates to the plating of pins on pin grid array packages using a removable metallic plating screen.
A common ceramic package for electronic applications is the pin grid array package wherein pins provide the inputs/outputs to the next level of packaging. Electroplating of the pins is employed to provide the pins with enhanced solderability, conductivity, and/or immunity to corrosion.
It is necessary to electrically short all of the pins during electroplating. This may be accomplished by shorting the pins internal to the ceramic package. As this is often impractical, the pins are usually electrically shorted external to the ceramic package by any of various means.
With the increasing complexity of ceramic packages that includes a large number of densely situated pins to be plated, the task of electrically shorting all of the pins becomes more complicated since any apparatus that contacts (and electrically shorts) all of the pins must necessarily restrict the flow of the electrolyte, thereby adversely affecting the plating of the pins.
Noto U.S. Pat. No. 5,342,992, the disclosure of which is incorporated by reference herein, discloses an electrically conductive plate that contacts all of the pins. Contact with the plate is provided by pin-clasp contacts. A difficulty with the disclosed apparatus is that the muliple pin-clasps make the plate difficult to remove while if there is only one pin-clasp, contact with the pin may not occur if the pin is bent.
Shibata et al. U.S. Pat. No. 5,580,432, the disclosure of which is incorporated by reference herein, discloses a plating jig for plating pin grid arrays which is placed over the pins and then laterally moved to cause a force fit between the plating jig and the pins.
Canaperi et al. U.S. Pat. No. 5,516,416, the disclosure of which is incorporated by reference herein, discloses an apparatus for plating pin grid arrays wherein the pins are electrically shorted by being pressed against an electrically conductive foil. This apparatus works well except that when the number of pins increases, the electrolyte becomes depleted before it can reach the centrally located pins.
Roll et al. U.S. Pat. Nos. 5,022,976 and 5,087,331, the disclosures of which are incorporated by reference herein, disclose a plating jig on which is clipped the pin grid array package. The plating jig comprises metal bars or pegs which make contact with the pins. According to the teachings of this patent, the pins must first be bent before being clipped to the plating jig.
It is a purpose of the present invention to provide an apparatus and method for electroplating pin grid array pins that is an improvement of the prior art.
It is a further purpose of the present invention to provide an apparatus and method for electroplating pin grid array pins that electrically shorts all of the pins.
It is yet another purpose of the present invention to provide an apparatus and method for electroplating pin grid array pins that utilizes a metallic screen that contacts all of the pins.
These and other purposes of the present invention will become more apparent after referring to the following description in conjunction with the accompanying drawings.